Thermal squeezeout of dark matter

Detailed Calculation of Primordial Black Hole Formation During First-Order Cosmological Phase Transitions

“…Similarly, the physics of early Universe phase transitions has become a popular topic in recent years, again driven by the prospect of observing gravitational waves from these phase transitions in upcoming experiments [28][29][30][31][32][33][34]. Besides significant advances in our understanding of the dynamics of these phase transitions [35][36][37][38][39] and in our computational techniques [40][41][42][43][44][45][46], phase transitions have been widely used as phenomenological tools, for instance to explain the baryon asymmetry of the Universe via electroweak baryogenesis [47][48][49][50][51][52][53][54][55][56][57][58][59] and other mechanisms [60][61][62][63][64][65][66], to form DM "nuggets" [67][68][69], or to set the abundance of particle dark matter [70][71][72][73]. Most r...…”

Supercool Composite Dark Matter Beyond 100 TeV

“…We have studied the signals of the model at gravitational waves interferometers, colliders, direct and indirect detection experiments, for the cases where DM is a heavy scalar, 17 Other ways to evade this bound are, for example, DM dilution after a matter era [128,[218][219][220][221][222][223][224][225][226][227], or having a dark sector being much cooler than SM [237,238], DM becoming heavy only after freezing-out [239], DM annihilating with one spectator field [240] or with many of them [241], DM forming an extended object which undergoes a second annihilation stage [228][229][230]. Mechanisms involving phase transitions include the possibility of a short inflationary stage associated with perturbative DM mass generation [147], DM filtered [231,232] or squeezed-out [233,234] by non-relativistic bubble wall motion, DM produced by elastic bubble-bubble collisions [235] or perturbative plasma interactions with relativistic walls [236]. (In contrast with these last possibilities, the mechanism which we studied in [45] and which we review in the present work, relies on a strongly interacting theory, with relativistic bubble walls, which come from effective potentials which result in inelastic bubble wall collisions.)…”

Friction pressure on relativistic bubble walls

“…Indeed, k ⊥,i is the transverse momentum relative to the actual emitter and because of the successive recoils, it must differ from the absolute transverse momentum k⊥,i relative to the initial incoming momentum p a in Eq. (14). Instead, upon taking into account successive transverse recoils, Eq.…”

“…Cosmological 1st-order Phase Transitions (1stOPTs) have been the subject of a lot of interest because they can generate Gravitational Waves (GWs) [2][3][4], set the abundance of dark matter [5][6][7][8][9][10][11][12][13][14][15], explain the baryon asymmetry [16][17][18][19][20][21][22][23][24], generate primordial black holes [25][26][27][28][29][30], primordial magnetic fields [31], or topological defects [32][33][34]. A key quantity for the physics of these transitions, and in turn for most of their applications, is the wall velocity v w , which is set by the friction pressure on the bubble walls.…”